Wednesday, August 14, 2019

August wood in Swindon

Epilobium montanum

Exciting things that happen when you go looking for willowherbs...

A couple of days ago I was walking along one of West Swindon's many pedestrian paths, heading for Lidl and thinking about willowherbs, as documented in a recent post. There were masses here, but I felt self-conscious, with all the other passers-by, so I decided to duck into the wood I was passing and see if I could find some willowherbs that I could look at closely without feeling like an eccentric. As you can see, I succeeded: Broad-leaved Willowherb, Epilobium montanum. I was just leaving when I realized there were some other plants here that were far less commonplace. Right next to the trading estate, I began to have the feeling I'd blundered into Jurassic Park.

Lithospermum officinale

The first was this one. I was struck by the shiny lilac beads on the plant: at first I supposed they were unopened buds, but then I realized these were the fruits.

Lithospermum officinale, nutlets

I didn't have time to check my books, so I put an image up on the Facebook Wild Flower group, and was told that this is Common Gromwell (Lithospermum officinale); the fruits (nutlets) will later turn white. The plants grow up to a metre tall: there were loads of them here. The leaf-veins are distinctive, being deeply incised on the upperside, and correspondingly raised on the underside.

Lithospermum officinale, upperside of leaf

Lithospermum officinale, underside of leaf

Lithospermum officinale, young plants. Swindon, 26 September 2019.

And I noticed another unfamiliar plant too, with divergent branches bearing strange burr-looking fruits.

Cynoglossum germanicum in fruit

Fruits of Cynoglossum germanicum

Once again I consulted the Facebook group, and it seems to be Green Hound's-tongue (Cynoglossum germanicum), a very rare plant and apparently not previously recorded in Wiltshire. I've submitted the record and it's currently awaiting adjudication.

On a re-visit today, I realized there are lots of them here. I counted 62 fruiting plants,  then 67 on a recount a few days later. And there are hundreds of "first year" plants in the leafing phase. (Cynoglossum germanicum is one of those biennials in which the "first year" is often, I suspect, repeated for several years in a row.)

A tangle of Cynoglossum germanicum

Cynoglossum germanicum, stem and leaves.

Tongue-shaped leaves, fresh green, rather sparsely hairy. Whereas the leaves of common Hound's-tongue (Cynoglossum officinale) are grey-green and densely hairy. These ones felt smooth on the upper surface and softly bristly beneath.

Cynoglossum germanicum, leaf

Cynoglossum germanicum, fruiting plant surrounded by young plants

Cynoglossum germanicum, young plants

A strange place! The trees are not very old, about 50 years maybe. They're a mixture: Field Maple, Ash, Oak, Common Lime, Horse Chestnut, Wild Cherry, Cherry Plum, Crack Willow...

On a later visit I found a dozen Nettle-leaved Bellflower plants and a big clump of Balm. Other ground flora: Garlic Mustard, Woodruff, Stinging-nettle, Herb Bennet, Red Campion...

Cherry Plum: alternate toothed leaves and hairless green twigs.

Woodruff (Galium odoratum). Swindon, 26 September 2019.


Running across this colony of Green Hound's-tongue started me off on an investigation that absorbed me for nearly a year, until I left Swindon and moved to Frome, forty-five miles to the SW.

I heard back from the Vice-County Recorder, who told me that its presence in Swindon was known and that it had been introduced, but could give no other details. The BSBI map does show it now.

In a way that made sense. A small copse within a large conurbation is not usually a place you'd expect to discover a very rare native plant. 

But I was also puzzled. This site, with its c. 600 plants, was clearly well-established and self-sustaining. Attempts to introduce a rare plant aren't often as successful as this. Rare plants are rare for a reason. The usual reason is that few places meet their needs. And this species is biennial. A colony needs to keep setting seed or in a couple of years it'll be gone. 

Besides, by now I'd found Green Hound's-tongue in woodland on Shaw Ridge, about a mile from where I first saw it. And I kept on finding it. The complete list of sites is below, though I'm removing the grid references (email me if you need them). 

Was this a puzzle about plants, or a puzzle about human beings? What would motivate a person (or several persons) to introduce a plant on this grand scale; to make efforts that were at least concerted, not to say obsessional?

All of the sites, except perhaps Site 1, look like secondary woodland. There's no sign of old trees. Nevertheless there's some other interesting plants. I've mentioned Common Gromwell (Sites 1 and 5, and in other places on Shaw Ridge). There's a small colony of Nettle-leaved Bellflower at Site 1. Site 6 has Wood Anemone, Betony and Columbine. There's lots of Pignut in another Shaw Ridge wood near to Site 2. Were some of these other plants introduced too? 

Green Hound's-tongue is interesting to wild flower twitchers, but it's not a showy plant. The flowers are nice enough but they are small and few in relation to the plant's size, and you wouldn't notice them unless you were looking for them. The flowering time (late April/early May) is actually when the plants are least visible. On Site 1, for instance, they are buried among masses of Garlic Mustard and other plants. I was lucky to wander in there in August when all this other growth had died back, revealing the Green Hound's-tongue and its fruiting heads.

Green Hound's-tongue sites in West Swindon

1. By the river Ray . About 600 plants. Mostly at one end of a small wood, but I found one plant at the other end. 67 fruiting heads in 2019.

2. Ramleaze. 46 plants. Flowering 23/4/20.

3. Top of Shaw Ridge and on the slope down to the road. Nine plants. Four plants flowering on top, one on the slope 4/5/20.

4. Near Site 3, above the village hotel. 24 plants.  Another two near the path. All under pine.

5. Shaw Ridge, across footbridge from Site 3, on the edge of the wood. Seven plants, seen again on 2/4/20. With Common Gromwell and a vetch that I failed to re-find. Two plants flowering, 4/5/20. A further seven plants found 4/5/20 in the middle of the wood, on path by woodpile.

6. Near Site 4. Above the bowling alley. Among Wood Anemone. 114 plants mostly in a straggling line near the conservation volunteers' fence (six on the other side of central path) Under field maple etc. With Columbine, Betony.

Cynoglossum germanicum: the first flower I saw. Swindon (Site 2), 23 April 2020.

Cynoglossum germanicum: first flowers. Swindon (Site 2), 4 May 2020.

Cynoglossum germanicum: the flowers in relation to the whole plant. Swindon (Site 2), 4 May 2020.

Cynoglossum germanicum: later flowers. Swindon (Site 1), 20 May 2020. 

These later flowers all hang down and it's much harder to take a decent photo!

Common Gromwell (Lithospermum officinale) in flower. Swindon, 20 May 2020.

Nettle-leaved Bellflower (Campanula trachelium). Swindon (Site 1), 16 July 2020.

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